<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>hello
    <script>
        function f(data) {
            alert(data)
        }
        // fetch('http://127.0.0.1:91/').then(res=>res.text()).then(data=>{
        //     alert(data)
        // })
    </script>
    <script src="http://localhost:91?callback=f"></script>
    <!-- <button class="btn">点击</button>
    <script>
        const button = document.querySelector('.btn')
        button.addEventListener('click', () => {
            console.log('点击')
            fetch('http://localhost:80/')
        })

        const callback = () => {

        }

    </script>
      

</body>

</html>